1. Field of the Invention
This invention relates to ribbon cartridges, such as used in typewriters and printers and the like, and more particularly to improvements in such cartridges.
2. Discussion of Prior Art
Most known ribbon cartridges, used in typewriters, printers and the like, comprise a supply spool for holding a supply of ribbon, a take up spool for winding ribbon after use, both contained in a case. The takeup spool is rotated according to printing operation by a driving roller to wind the ribbon about the takeup spool and off the supply spool, at a fixed winding rate.
As illustrated, for example, in FIG. 1A, which depicts a known ribbon cartridge, a takeup spool 1 is rotated to wind up a ribbon 5, by a drive roller 4 having a plurality of teeth 2 along the circumference thereof. The drive roller is connected to a drive shaft of a motor, not shown, or the like. One end of torsion spring 7 engages stud 6, projecting from the center of an upper surface of the takeup spool 1, to bias the takeup spool 1 continually in the direction of arrow A, as indicated in FIG. 1A, so that takeup spool 1 is rotated by drive roller 4. This construction, however, is disadvantageous, in that, the resilient force of torsion spring 7 tends to tilt the takeup spool 1 in the direction of arrow B, as indicated in FIG. 1B. Torsion spring 7, as can be appreciated, applies biasing force to stud 6, which extends upward from the upper surface of spool 1. Thus, the spool 1 is caused to be tilted by the biasing force of the spring 7 acting on stud 6. This tilted position of spool 1 causes tape 5 to move away from a substantially vertical position after printing and be disaligned while being wound on spool 1. Spool 1 of the prior art devices, cannot wind ribbon 5 in a regular aligned manner and proper ribbon winding is never attained. The disalignment can cause entanglement, and interruption of regularity of printing. Speed is not completely reliable.
Thus, there exists in the art, a need for a ribbon cartridge which can reliably, properly and accurately wind up ribbon, without such ribbon cartridge being increased in price.